Instead of slicing horizontally or vertically, we slice radially.

取代横向纵向切割的是，我们沿半径切割。

youdao

And so that energy goes out radially, symmetrically, isotropically in all directions, and so it's very easy.

因此能量是呈放射状的，对称的，等效全向的辐射，向各个方向，因此很简单。

youdao

In some cases, it is actually even making more sense maybe to go radially, start out from the origin to your end point.

某些情况下，从原点到终点沿径向走，可能更有意义。

youdao

er is a vector at each point of length one pointing radially away from the center.

r 是一个模长恒为 1 的矢量,方向沿半径向外

耶鲁公开课 - 基础物理课程节选